Fuel system for combustion apparatus



June 10;,y 151952 T. a. DlLwoRTH ET AL 2,599,699

FUEL SYSTEM Fon coMBusTloN APPARATUS Filed May 15, 1947 (M Gttornegs Patented June 10, 1952 FUEL SYSTEM vFon coMBUsTIoN Motors Corporation, .tion of Delaware ioclaims. l

/V This invention relates to fuelsystemsfor com* bustion apparatus.

The principal 4object of the invention is -to provide fuel circulating means capable of sup- Diving more fuel than the fuel injectors of the combustion apparatus can deliver and prviding means for controlling the mixing lof the cold fuel from `a storage `tank with the `heated excess fuel returned lfrom ythe .injectors thereby preventing waxing and icing of the :filters V:lncluded in the fuel 4circulating system.

The combined means .for accomplishing the above object will become apparent by reference to the following description and drawing illustrating these means included in a fuel system which is particularly adapted forfsupplying fuel to a diesel engine which Vis operated under `wide and sudden changes in ambient temperature, humidity.. barometric pressure, speed, load and output conditions such .as encountered in diesel locomotive operation.

Figure 1 of the drawing .is Va `diagramrnatic View of the complete fuel system.

Figure 2 is anenlarged transverse sectional View of one of the control elements .shown in Figure 1.

Figure 3 is a sectional view on line V3-.3 Iof Figure 2.

Figure 4 is an enlarged verticalsectional view of another control element .shown in Figure .1.

As shown schematically in Figure 1 asplurality of fuel injection pumps "l :are operated by `a diesel engine, not shown. -These pumps :are provided with inlet and .outlet .nlters 3 .and are connected between a fuel pressure supply pipe '5 and ia'xfuel return pipe l. .Each of fthe injection pumps .I is associated with .an engine cylinder and is provided with means, fnot shown, `for Aspraying tuel at high pressure Linto the cylinder mcmbustion space in conventional manner. A .control rack 9 is shown interconnecting the injection pumps I for controlling the amount of `-fueljnjected per stroke in a -well known manner. 'Bhe lcontrol rack may be operated `manually .or by means of an engine governor win conventional manner. Fuel is supplied to theffuelpressure supply `pipe by a suitable engine or motor driven `fuel transfer pump Il which is capable of .supplying .fuel in excess of the maximum amountef fuel .discharged by the injection pumps. 'Fuel'from the transfer pump Il reaches 'the fuel pressure supply pipe 5 through pipe connections .|3--I5 which include a filter ll and Va conventional pressure relief valve 'for .protecting the system from excessive pressure. The inlet .side of "the APPARATUS Thomas B. Dilworth, C1

arendon Hills, and vMilo M. fschalla, Oak Lawn,

Ill., assignors `to General Detroit, Mich., a corpora- Application May 13, 1947, VSerial No. 74??,758

`2 fuel transfer pump I 1i is :shown `connected by means of pipes 2|-23 and :a filter 25 to a vthermostatic mixing valve. A .fuel inlet pipe 19 yis connected between the mixing valve and a main fuel tank and extends substantially to the ibottom thereof.

The fuel return pipe :and a pressure relief pipe 21 ffrom `the pressure relief valve arefshown connected to the upper portion of a fuel return tank. An .overflow pipe 29 is also ,shown connected .between the upper .portions of the 4fuel return and `main fuel tanks. A fuel return Aconnection 3l .including a shutoi valve 33 is shown connected between .the bottom of the return tank and the thermostatic mixing valve. The Vmain tank .is Lshown v'provided with .-,a filling opening closed with a removable cap 35 `and an atmospheric vent ,31.

b est illustrated .in Figure 4 the thermostatic fmixing 'valve comprises a hollow valve body .3.9 having ahollow seatelement 4I secured in one end and extending through a larger interna-1 diameter portion of the valve body to form an annular slot #l2 therebetween. The valve body V3.9 Wis .provided :with a threaded .inlet opening 43 to which the fuel return connection 3l ,from the fuel return tank is connected. The valve body C39 is `also provided with a threaded inlet .opening A5 to which the inlet pipe |29 from the lma'in .fuel tank :is Vconnected and .a threaded outlet opening il to `which the pipes 2li-423 and filter 25 leading 4to the inlet side of the transfer pump l 1| are connected. The threaded fuel return and inlet connections `#i3 and 45 Ain the valve body 39 are shown 'located on one -side of the annular slot 42 between 'the -hollow seat element M and val-ve -body and the kthreadedoutlet connection `47 inthe body -is shown located von the opposite side of the yslot '42. A plug V49 is threaded iin `the other end -of `the `valve body 39 and has Aa `thermostatic element 5| secured to the inner `face of `the plug. A `valve head j5t is secured to the inner face ofthe thermostatic element 5=| and 'is Amovable thereby vfrom `the normal open position, shown, linto seating -contact 4with the "inner Yend of the hollow 4seat 4element El upon expansion of the thermostatc element 5I `when ztne `tempera-ture of `the fuel in 4:contact `therewith `reaches a temperature of It lwill .be evident that when the valve head 53 is seated on 'the Valve seat '41, communication ,is cut o'ii between the fuel return .connection `3l of the return tank and the fuel inlet connections `l`9-2.l-23 and lteri25 to the inlet ofthe transfer .pump "II, however the threaded fuel inlet and outlet connections 45 and 41 in the valve body being in communication through the annular slot i2 permit fuel flow between these connections and fuel inlet pipe connections |9-2|-23 and lter 25 to the inlet of the fuel transfer pump As best illustrated in Figures 1, 2 and 3, the fuel return pipe 1, the pressure relief pipe 21 and the overflow pipe 29 are connected to the fuel return tank at substantially the same level and baiiies 55--51 are secured in the return tank adjacent the open ends of these pipes to aid in separating the air and occluded vapor in the fuel entering the return fuel tank through the pipe 1 and to insure that the separated air, vapor and some excess fuel is diverted from the upper portion of the return tank through the overflow pipe 2S directly to the main fuel tank. As best illustrated in Figures 2 and 3 a balanced float control valve indicated generally at 59 is secured to the bottom of the return tank on the other side of the tank baffles 55-51. The valve 59 comprises a housing 60 having a central inlet cavity 6| opening into the interior of the return tank below the level of the baffle 51 and provided with vertically aligned valve seat openings 53-55 and an exterior outlet cavity 51 surrounding these seat openings and communicating with an opening 69 in the bottom of the return tank to which the fuel return pipe connection 3| is connected. A fioat ii is secured on an arm 13 which is pivoted to the valve body at 15. A valve stem 11 is slidably mounted in an opening in the exterior outlet cavity 61 of the valve body 60 and is pivotally connected at 19 to the arm 13 for vertical movement by the float 1|. The valve stem 11 is shown provided with two valve heads 8|-83 which are seated on the valve seat openings 63-55 when there is minimum fuel in the return tank and the float 1| is accordingly at the lowest position in the return tank as shown in Figure 3. It will be evident that with the valve heads 8|-83 seated, suction of the transfer pump is applied to the upper face of the valve head 8| and to the lower face of the valve head 83 when the thermostatic mixing valve is open and the lower face of the valve head 8| and the upper face of the valve head 83 are subjected to the pressure head in the return tank to provide a substantially balanced pressure valve construction which is accordingly operable by slight movement of the float 1|. It will likewise be evident that the higher the level of fuel in the return Jtank the farther the valve heads 8|-83 will be moved off the seat openings 63--55 and the greater the amount of return fuel flow therethrough to the return connection leading to the thermostatic mixing valve.

With the injector control rack 9 in the starting position and the other control elements in the normal position as shown, as soon as the transfer pump and engine are started, cold fuel at less than 65 F. will be supplied from the main fuel tank by the transfer pump to the injection pumps in an amount greater than the maximum amount delivered by these pumps through the pipe connections I9, 2|, 23 including the thermostatic mixing valve 39 and filter 25 and pipe connections |3, |5, 5 including the pressure relief valve, filter |1 and injector inlet filters 3, the excess fuel flowing through the injectors will be heated and flow through the injector outlet filters 3 and fuel return pipe 1 to the fuel return tank. The pressure relief valve normally remains closed but opens upon excess pressure upon cloggin of filters |1 and 3. Upon starting of the engine the fuel control rack is normally moved back to the idle fuel position to permit proper warm up of the `engine at idle speed. At this speed the `majority of fuel delivered to the injector pumps passes through these pumps and is heated and returned through the injector outlet filters 3? and return pipe 'l to the return tank. Some of 'ithis .heated fuel and the vapor therein is returned by the baffles in the return tank directly to" the main fuel tank through the overow pipe t@ heat the fuel therein. The remainder of this lleated fuel flows over the baffle 51 in the fuel ,rturn tank causing the fuel level to increasef" therein and the float 1| of the valve 19 t`o rise and move the valve heads 8|83 away from theirseat openings in proportion to the increasel in\.fuel level in the return tank. The fiow'of heateid fuel from the return tank through the return corrinection 3| to the then open thermostatic mix\\ ing valve is proportional to the level therein and hence more heated fuel will be drawn bysthe transfer pump from the return connection 3| than from the inlet pipe I9 carrying cold fuel from the main tank. This greater amount of warm fuel and any water mixes with the smaller amount of cold fuel from the main tank in the space surrounding the thermostatic element 5| of the mixing valve and is circulated by the transfer pump and thus prevents initial waxing and icing of the filter elements in the system in freezing Weather thereby preventing restriction or cutoff of fuel flow. When the level of fuel in the return tank causes overflow of heated fuel through the overflow pipe 29 to the main tank, the float valve 59 is open to the maximum extent and the maximum amount of heated fuel is accordingly circulated by the transfer pump When the injector fuel rack 9 is moved to cause more fuel to be discharged per stroke from the respective injection pumps and a corresponding increase in the engine speed, load and output there is less excess fuel returned to the return tank and this fuel is accordingly heated to a greater degree. This causes a decrease in the level of fuel in the return tank and the float 1| therein will fall and move the valve heads 8|-83 toward the seat openings 63-55 and restrict the flow of this hotter return fuel to the mixing valve which causes more cold fuel from the main tank to mix therewith for circulation by the transfer pump When the temperature of mixture of hot return fuel and cold fuel from the tank Surrounding the thermostatic element 5| of the mixing valve reaches 65 F. the valve head 53 therein is seated. This condition occurs when the fuel in the main tank reaches 65 F.,

or above, and accordingly no return fuel from the return tank can enter the mixing valve, the return fuel from the injection pumps then passes from the return tank through the overflow pipe 29 directly to the main tank and fuel feed continues to the fuel injection pumps via the inlet pipes |92|23 and annular slot 42 in the mixing valve 39. For warm weather operation where the temperature of the fuel in the main tank is above 65 F. the shutoff valve 33 in the return connection from the return tank to the mixing valve may be shut off manually if desired.

With the above described fuel system it will be evident that in freezing weatherV the greater the amount of heated return fuel the less the attacco cold fuel is mixed therewith for circulation in the system 'and 'conversely the lesser the amount of heated 4fuel `returned the :greater "its temperature 'and the greater the amount of cold Tfuel is mixed therewith for circulation by the 'transfer pump Il `through the system.

This fuel system provides the means to prevent icing and waxing lof the filters provided in fuel `systems Vfor combustion 'devices operated under extreme load l'and freezing 'atmospheric conditions.

We claim:

1. Ina -fuel system for combustion apparatus, fuel injection means adapted fto be associated With and `heated by the combustion apparatus and adapted to deliver variable quantities of fuel directly thereto, a main fuel tank, fuel supe ply 'connections including :a mixing valve, filters and a transfer pump `inte'rconnacting lsaid inain tank :and said injection means for supplying fuel thereto in excess of the maximum quantity delivered thereby to cause heating of the `excess fuel in said fuel injection means, a -fuel return tank for receiving the Aheated excess fuel from said injection means, said return tank having a fuel return connection with the fuel injection means, an overflow connection V`with said main fuel tank, a return fuel connection with said mixing valve, a lfloat controlled valve `in the re1- turn tank for controlling the vflow of heated fuel in the return connection to said mixing valve in proportion to the level in said return ytank for Warming the fuel from said main tank Ain passing through said `mixing valve to prevent icing and waxing of said filters, and temperature responsive means in said mixing valve for shut-ting off the flow `of heated return fuel -to said mixing valve when the temperature lof the fuel mixture therein reaches a preselected value.

2. -In a fuel system for combustion apparatus, a fuel injector adapted to be connected to and to receive heat from the combustion apparatus and 'adapted to deliver fuel thereto, a fuel tank, means including fuel supply connections 'including a pump and a filter and interconnecting said tank and said injector for supplying fuel from said tank to said ilnjectorin excess of the amount delivered thereby 4so that the excess fuel is heated in said injector, a fuel return connection interconnecting said injector and said tank and 4a second 'fuel return connection interconnecting said rst fuel return connection and -said fuel supply connections ahead of said filter, said second fuel return connection including temperature responsive control means for controllingtlie `amount of 'excess heated fuel from said injector to said fuel supply connections ahead of said filter to Warm the fuel supplied from 'said tank and prevent icing Aandwaxing of said filter.

3. In a fuel system for combustion apparatus, fuel injection means adapted 'to be intimately associated with and heatedby the combustion apparatus and adapted to deliver fuel directly to the combustion apparatus, a 'fuel tank. fuel supply connections including alte'r and a pump interconnecting said tank and said fuel injection means for supplying -fuel from said tank to said fuel injection means in excess of the amount delivered thereby so that the excess fuel is heated in said fuel injection means, a return fuel connection interconnecting said fuel injection means with said tank, a second fuel return connection interconnecting said fuel injection means with said supply connections ahead of said filter, said second fuel return connection including a valve ucontrolling the -return of some of the heated fuel from said injection. means to said tank and some of the heated fuel, in pro portion to `the excess supplied thereto. fdirectly to said fuel supply connections ahead `of said filter to warm the cold fuel 4in the supply `connections from said tank and prevent icing and Waxing of said iilter, and a second valve means responsive to a predetermined temperature of the mixture of fuel ahead of said filter in the supply connections to stop the flow of heated return fuel to the fuel supply connections.

4. In -a fuel system yfor Acornbiiistion apparatus. a `plurality of fuel injectors r'adapted to be mountied on and be heated by said apparatus and adapted to inject fuel into said 'apparat-us, means 4for controlling the amount of fuel Aide*- livered `loy `said injectors, said injectors having fuel inlet Vand 'outlet filters, a main fuel tank, fa fuel vtransfer pump Shaving fa fuel ,inlet pipe connected to said main tank land including a mixing valve 'and Ia Vfuel pressure supply pipe Iconnected to said injectors and including a fuel filter and a pressure relief valve, said transfer pumploeing fcap'able of supplying fuel in excess of the maximum amount Idelivered by said in'- jection pumps, the yexcess fuel `being heated in said injection pumps, a fuel return tank for receiving `the heated excess fuel from. said Ein- Jectors, an excess return `fuel connection interconnecting the upper portion vof said return tank and the outlet filters of said injectors, over*- ilow connection interconnecting the upper 'portion of :said return tank to vsaid main fuel tank to convey heated fuel and vapor thereto, a reiturn fuel connection from the lower portion of said return tank 'to said mixing valve, a float controlled valve in said return tank and connected to the return connection lfor controlling the flow of heated fuel to said mixing 'valve in proportion to fthe fuel level in said return tank, the heated fuel iin said mixing valve vmixing with the cold 'fuel from the main tank preventing icing and Waxing of said lters, Vand means responsive to la preselected 'temperature lof the fuel 'mixture fsa-id `mixing valve for shutting olf the now of heated fuel thereto.

5. Ina fuel system for combustion apparatus, variable delivery fuel injection pumps adapted to be associated with and heated by the coinbustion apparatus and adapted to inject fuel therein, said injection pumps having fuel inlet and return 1filters, a main fuel tank, :a return fuel tank, a fuel transfer pump having a fuel inlet "connection to the main tank, said Aconnection including a mixing valve and a filter and an outlet connection including `a 'filter and an excess pressure relief valve and Aconnected to the inlet filters 'of the injection pumps, said transfer pump delivering fuel in excess to that delivered by the injection pumps, said fuel return tank including baiiles, an excess fuel return connection, a pressure relief connection and van overflow connection connected to the upper portion of the return tank on one side of the 'baiiies therein, 'said ex'cess vfuel return connection being 'connected to "the outlet filters of the'injection pumps for conveying the excess fuel heated therein to the return tank, said overflow connection being connected to the main tank to convey heated fuel and vapor thereto, said pressure relief connection being connected to the excess pressure relief valve, and a fuel connection from the lower portion of the tank on the other side of the loaiiles therein connected to the' mixing valve, a float controlled valve in the return tank at the entrance of the fuel connection to the mixing valve operable to vary the flow of heated'return fuel from the return tank to the mixing valve in proportion to the level of the fuel in the return tank to warm the fuel in the inlet connection to the transfer pump ahead of the filters to prevent icing and waxing of the filters, said mixing valve having a temperature responsive element for cutting off the flow of heated fuel from the return tank when the temperature of the fuel mixture in the mixing valve rises to a preselected value so that fuel from the main tank is then supplied to the injection pumps.

6. In a fuel system for combustion apparatus, a variable delivery fuel injection pump adapted to be associated with and heated by the combustion apparatus, a main fuel tank, fuel supply connections including a mixing valve, a lter and a fuel transfer pump interconnecting said main fuel tank and said injection pump for supplying fuel in excess of the maximum amount delivered by said injection pump to cause heating of the excess fuel in said injection pump, a fuel return connection extending from said fuel injection pump to said mixing valve, said fuel return connection including control valve means operable in response to thev amount of heated excess fuel returned from said fuel injecting pump to cause a proportional amount of heated fuel to enter said mixing valve to mix with and warm the cold fuel supplied from said main tank to prevent icing and waxing of said filter, and a branch fuel return connection extending from said fuel return connection ahead of said control valve means to the main tank for the return of the remainder of the heated excess fuel to said main tank.

7. In a fuel system for combustion apparatus, variable delivery fuel injection pumps adapted to be associated with and heated by the combustion apparatus and adapted to inject fuel therein,ra main fuel tank, fuel supply connections including a mixing valve means, fuel filter means and a transfer pump interconnecting said main tank and fuel injection pumps for supplying fuel thereto in excess of the maximum amount injected into the combustion ap-paratus in order to heat the excess fuel therein, a fuel return connection for the heated excess fuel extending from Y.said fuel injection pumps to said mixing valve, temperature responsive means in said mixing valve to cut olf entry of heated return fuel to said mixing valve upon a rise in temperature therein above that necessary to prevent icing and Waxing of said filters, and a branch fuel return connection extending from said return fuel connection ahead of said mixing valve to said main fuel tank.

8. In a fuel system for combustion apparatus, the combination of variable delivery fuel injection means adapted for injecting fuel in and adapted to be heated by the combustion apparatus, a fuel supply tank, fuel supply connections extending from said tank to said fuel injecting means and including fuel filters, a mixing valve and a fuel supply pump for delivering fuel to said fuel injection means in excess of the maximum amount injected thereby into` the combustion apparatus and a `fuel return connection leading from said fuelinjection means to said mixing valve, said fuel return connection including valve means acting in response to the amount of heated excess fuel entering said fuel return connection to` cause a proportional amount of heated fuel to enter said mixing valve to mix with and warm the fuel entering said mixing valve from said tank to prevent icing and waxing of said filters in said fuel supply connections, temperature responsive means in said mixing valve to cut off entry of heated excess return fuel upon a preselected rise in temperature of the fuel mixture therein and a branch fuel return connection extending from4 said fuel return connection upstream from ,-said valve means therein to said fuel supplytank. 9. In a fuel system for combustion apparatus,

fuel injection means adapted to inject fuel into and adapted to be heated by the combustion apparatus, a fuel supply tank, fuel delivery means for delivering fuel from the tank to the injection means at a rate normally in excess.

of that at which the fuel is injected by the injection means, fuel return means for returning the heated excess fuel from the injection means to both the tank and said delivery means,` and temperature responsive means responsive to the fuel temperature in said delivery means for controlling the return of said excess fuel to said delivery means.

10. In a fuel system for combustion apparatus, a fuel charge-forming device adapted to heat fuel delivered thereto and to subject a portion of said heated fuel to combustion, a fuel tank, fuel delivery means delivering fuel from the tank to said device at a rate exceeding the rate fuel is subjected thereby to combustion, fuel return means returning the heated excess fuel from said device to the tank, said return means having branch means by-passing the tank and connected with said delivery means, valve means in said branch means` operable in response to fuel temperature in said delivery means for cutting off fuel iioW through said branch means.

THOMAS B. DILWORTH. MILO M. SCHALLA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,348,406 Green Aug. 3, 1920 1,854,603 Robinson Apr. 19, 1932 1,867,491 Braren July 12, 1932 1,962,448 Kreuzer June 12, 1934 2,062,644 Ensign Dec. 1, 1936 2,133,394 Mortier Oct. 18, 1938 2,157,737( Janssen May 9, 1939 2,199,454 ,y Andler et a1 May 7, 1940 2,262,617 LOrange Nov. 11, 1941 FOREIGN PATENTS Number Country Date 438,854 Germany Dec. 28, 1926 

